The association between hordein polypeptide banding and agronomic traits in partitioning genetic diversity in six-rowed Ethiopian barley lines (Hordeum vulgare L.)

Abstract

Background: Evaluation of the extent of genetic variation within and between the populations of crop genetic resources are of paramount importance in any breeding program. An experiment aimed at assessing the extent of variation among barley lines and the degree of association between hordein polypeptide and agronomic traits was hence executed.

Methods: Field experiment was conducted in six environments between 2017-2019 involving 19 barley lines. Hordein bands were separated using vertical Sodium Dodecyl Sulphate Poly- acrylamide Gel Electrophoresis (SDS-PAGE).

Results: The analysis of variance revealed significant variation among lines and wider range units were observed for the agronomic traits. The line (Acc# 16,811-6) was superior, producing the highest grain yield (2.97 ton ha^-1) across environments, 3.6 ton ha^-1 at Holleta, and 1.93 ton ha^-1 at Chefedonsa. At Arsi Negelle a different line Acc# 17146-9 was the highest yielding (3.15ton ha^-1). SDS-PAGE-based analysis of barley lines separated 12 hordein bands between C (four bands) and B (eight bands) subunits. Interestingly bands 52, 46a, and 46b were uniquely conserved in the four naked barley lines (Acc#16809-14,16956-11, 17240-3, 17244-19). A considerably high proportion of genetic diversity within the populations than among the populations could be a repercussion of high gene flow which substantiates the longstanding and dominant informal seed exchange system among the farmers. The significant positive association between grain yield and band 50 evocates the expression of this allele may code for higher grain yield. The negative association between days to maturity and band 52 perhaps stipulates earliness in barely lines upon the manifestation of the band. Band 52 and 60 appeared to be associated with more than one agronomic trait (days to maturity and thousand kernel weight; grain filling period and grain yield respectively) and could be the result of pleiotropic characteristics of the genes residing in these banding regions.

Conclusion: The barley lines exhibited substantial variation for hordein protein and agronomic traits. However, imparted the need for the implementation of decentralized breeding as a consequence of genotype-by-environment interaction. Significant hordein polypeptide and agronomic traits association advocated the utilization of hordein as a protein marker and perhaps consider them in the parental line selection.

Keywords: Barley; Genetic diversity; Hordein; Multiple regression; SDS-PAGE.

Fig. 1

Grain yield with the respect to the six test environments. The x-axis represents, the environments AN1 = Arsi Negelle year I and AN2 = Arsi Negelle year II; CH1 = Chefedonsa year I; HO1 = Holleta year I, and HO2 = Holleta year II. The y-axis represents the estimated grain yield in ton ha⁻¹

Fig. 2

Hordein polypeptides migration patterns in 19 six-rowed barley lines based on SDS gel electrophoresis from a single seed of barley lines, M = molecular weight makers with the molecular weight (kDa)

Fig. 3

Phylogenetic relationship among 19 barley lines based on unweighted pair group method where the geographic origin of the lines was as per the legend

Fig. 4

A map of Ethiopia showing the administrative regions and zones where the barley farmers’ varieties included in this study were collected (A) and the sites (districts) where the field experiments were carried out (B)